Control device



Oct. 14, 1952 J. w. MCNAIRY 2,613,630

CONTROL DEVICE Filed Jan. 22, 1947 2 SHEETS-SHEET 1 IISVOLTS Irwventor: Jacob W. Mc Nair y,

His Attorn ey.

Oct. 14, 1952 2,613,630

J. W. M NAIRY 4 CONTROL DEVICE 2 SHEETS-SHEET 2 Filed Jan. 22. 1947 nun Inven tor: Jacob W Mc Nairy,

is Attorney.

Patented Oct. 14, 1952 CONTROL DEVICE Jacob W. McNairy, Westport,,0.onn., assignorto. General Electric, Company, a corporation of.

New York ApplicationJanuary 22, 1947, Serial No. 723,549

2 Claims.

The present invention relates to control devices and more particularly to control devices for controlling the operation of a heating circuit so that the heat output of the circuit may readily be varied in small increments from a predetermined.

minimum to a predetermined maximum.

Still more particularly this invention relates to an illuminated indicator for a control device for anelectric circuit. While not limited thereto, this invention is especially useful in the control of electric blankets and similar heating devices in which the energization cycle of the device may be selectively'controlled by the operator and is further controlled automatically in aocordancewith ambient temperature variations.

This invention is an improvement in the control device described and claimed in Patent No. 2,429,475 issued October 21, 194'? in the names of J W. McNairy, F. A. Rosenkrans, and" A. E.

Coombs, and assigned to the sameassigneeas the present invention.

According to the present invention, an illuminated'j indicator is-provided to indicate when the heating device is turned on or off; to indicate by afluctuation in light intensity when the heating device is cycling properly; and to indicate the selected cycleof operation of the heating device.

A. more complete understandingof the inven tion will be had from the following description taken I in connection with the 1 accompanying drawings inwhich Fig. l. is aschematic view. of.

one modification ofthe-invention; Fig; 2.is a plan. View of the indicator with a portion'broken away to show operating element; Fig. 3 isan elevation,

of the. indicatingdevice with a portion broken away; and Fig. 4 is a diagram of a modification of the operatingcircuit shown in Fig. 1;

. Referring to the drawings, the load device I, in this caseillustrated as an electrically heated blanket is connected to a suitable electric power supplythrough a contact mechanism which turns theiheating element on and off ina periodic cycle asmay'bev selected by the blanketuser. The on-oif cycle is further automatically controlled by atemperature responsiveelement in accordance with; the ambient temperaturein which the temperature. responsive element is located. This mechanism is schematically shown inzFig. 1. The blanket l is-connected by conductor 2 to an arm 3 carrying a. contact 4 which cooperates with a fixed contact 5 to close the energizing circuit to the blanket I. tacts d and 5 is controlled by means of an auxiliary arm 6 actuated periodically by any suitable means as, for example, by an eccentric cam. I

which. may berotated through shaftqfl' by amotor such as, forexamplea clockmotor having an.

Opening and closin of the conenergizing winding 9. Between the auxiliary arm movable longitudinally in order to vary the length of time the contacts 4 and 5 are closed during each rotation of the cam l. The position of the wedge Iii is controlled in accordance with, ambient temperature variations bya temperature. responsive element H mounted at the end of the shaft E2. The position of the wedge, and there-- fore the heating cycle, may further be controlled by the blanket user bya manual adjustment-of the shaft i2. This is accomplished by means of an arm i3 fixed to the shaft l2 and a manually adjustable member and pointer M which is secured to the arm l3. Details of the foregoing mechanism are more fully described in Patent No. 2,429,475, referred to above.

Suitable illumination is provided to indicate the position of the pointer I4. so that the user may be able to see the selected heating cycle evenv in a darkened room. The preferred illuminating arrangement in accordance with my invention is as shown in the drawings. The pointer I4 is made of a translucent materialand preferably one having a high index of refraction, such as, for ex.- ample, of fused quartz or of a plastic such as polymerized methyl methacrylate. The pointer may be made integrally with a U-shaped element l5 between the arms of which there is mounted a lamp l6. From the bottom of the U there pro.- jects an ear H which curves upward to form the pointer Hi. The pointer 14 is mounted to cooperate with a scale l8 as shown in'Fig. 2. Thus, light from the lamp l6 passing into the pointer. at the bottom of the element 15 is transmitted through the ear IT and up into the pointer I4 causing the latter to appear luminous. Asshown in Figs. 2 and 3, the main light-receiving body'of the pointer I5 and the illuminating system is preferably mounted Within a casing so that only the ear I4 of the pointer projects through a narrow slot to the outside of the casing. The casing, thus acts as shield for the illuminating means, and the user of the device sees only the luminous glow of the pointer.

interposed between the lamp 5 and the elee ment [5 there may be placed a light filter: I9. This is divided into a number of transparent'sections, each of a different color. The element IS in Fig. 1 of the drawing is lined to showthe different colors. Suitable colors may; for: eX-

} ample; be; red, yellow, purple, green, blue-and:

white, with the red at the hot end of the; scale.- It will thus be apparent that when the selector is positioned as shown in Fig. 1 the pointer. I4

will glow with a white light while'if the. selector."

be, positioned oppositeonecf'. the other sections of the filter I9, the pointer I4 will glow with the color corresponding to its position. The user of the blanket can, therefore, readily determine, without close inspection, the degree of heat which has been selected. The light filter I9 has been shown divided into a plurality of sections of different specified colors by way of example only. Other colors may be used. The color bands may overlap. Also, a continuously changing color band may be used. Similarly, sections or a band of a single color varying in color intensity may be employed. Any of these will make readily apparent to the blanket user the setting of the control device.

A further feature of my invention consists in an arrangement whereby a fluctuation of the intensity of illumination of the pointer indicates whether or not the heat cycling mechanism is functioning properly. This ma be accomplished by the circuit illustrated in Fig. 1. A switch arm 20, shown in its open position, is arranged so that in its second position it will short circuit two contact studs 2! and 22. Contact 2I is connected to a low voltage winding 23 which may be wound in inductive relation to the motor field coil 9. The other end of winding 23 is connected in series with the lamp I6 to one terminal of a resistance 24. The second terminal of the latter is connected to contact 22. Thus, in the second position of the switch arm 20, the voltage produced by the winding 23 is applied to the lamp It in series with the resistance 24. With the switch arm 20 in the second position as just described, a circuit is simultaneously completed from the supply line through contact 22, resistance 24, contacts 4, 5 and conductor 2 to the blanket I, and thence back to the supply through conductor 2.

When the contacts 4 and 5 are open, the blanket I will, of course, be deenergized. However, when the contacts 4 and 5 are closed and current flows through the heating element in the blanket I, a voltage drop occurs across resistor 24. This voltage drop is in opposite polarity to the voltage produced by the winding 23, so that the operating voltage applied across the terminals of the lamp I6 is reduced. The lamp, therefore, glows only dimly when the heating circuit is closed. When the heating circuit is opened by the opening of the contacts 4 and 5, the lamp I6 receives substantially the full voltage of the winding 23 and glows brightly. Thus, as the cycling cam 'I rotates, the lamp I6, and consequently the pointer I4 will be alternately brightly and dimly illuminated for proportionate periods of time dependin upon the times during which the blanket is energized and deenergized. It will be evident from the foregoing description that the blanket user can determine at a glance not only the selected setting of the control device from the color with which the pointer I4 glows, but also from the fluctuation in the intensity of its illumination whether or not the system is operating properly.

It'will be noted that my use of polymerized methyl methacrylate or similar material in the construction of the pointer I4 substantially eliminates room illumination such as might be objectionable under sleeping conditions. By properly shaping the outer surface I4 of the pointer, substantially no light will be transmitted through this surface into the room but nearly all the light will stay inside the pointer which will have only a soft glow.

In the event that the user of the blanket does not wish to have any light at all, I have provided an additional contact 25 forming a third position for the switch arm 20. In this position, the lamp I6 is disconnected and the supply line circuit through the arm 20 and contact 25 passes directly through resistor 24 and contacts 4 and 5 to the blanket I, while at the same time the motor winding 9 is energized through a parallel circuit.

A modification of the operating circuit is shown in Fig. 4 in which similar elements are given the same reference numerals. Instead of supplying a separate winding in inductive relation to the motor field as in Fig. 1, the arrangement shown in Fig. 4 merely provides a tap 26 on the field winding 9. The lamp I6 is connected to the tap 26 and thence to terminal 21 of a three-position switch having a contact arm 28. The arm 28 is connected through resistance 24 to the end of winding 9 as well as to contact 5 of the cyclin mechanism. An additional contact 29 in cooperative relation to the arm 28 is connected to one side of the supply line; the other side of the supply line is connected by conductor 39 to the other end of motor windin 9, as well as to one end of the heating element of blanket I, through which the circuit is completed through contacts 4 and 5. Fig. 4 shows the switch arm 28 in the off position. In the second position of switch arm 28 the latter connects with both contacts 29 and 2! completing a circuit through contacts 4, 5 to the :blanket I, as well as connecting the lamp I6 across the low voltage tap 26 of winding 9 in series with resistance 24. Since the voltage drop in resistance 24 due to the flow of current through the heatin element of the blanket I is in the opposite polarity from the voltage appearing across the tap portion of the winding 9, the lamp IE will glow dimly. However, when contacts 4 and 5 open, the lamp will receive full voltage and will brighten. In the third position of switch arm 28, the latter makes connection only with contact 29. In this position a circuit is completed through the motor winding 9 and through contacts 4 and 5 to the heating element in the blanket I, but the lamp I6 is disconnected entirely.

While I have shown and described a particular embodiment of my invention, it will be obvious to those skilled in the art that various changes and modifications may be made without departing from my invention in its broader aspects and I, therefore, aim in the appended claims to cover all such changes and. modifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. In a control apparatus for an electric heating device, the combination of a housing having an elongated aperture therein, an adjustable element movable with respect to said housing and having a U-shaped portion within said housing and an operating portion extending outside of said housing through said aperture for manual adjustment, said element being formed of a translucent material having a high index of refraction, illuminating means carried between the legs of said U-shaped portion, and a light filter disposed between said illuminating means and said element for varying the light transmission corresponding to adjustment of the position of said element.

2. In a control apparatus for an electric heating device, the combination of a housing having an elongated slot therein, an adjustable element REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Name Date Wells Apr. 21, 1925 Number Number Number 6 l Name Date Wilhjelm June 24, 1930 Van Reet-h July 22, 1930 Hickman Mar. 24, 1931 Lohe May 25, 1937 Klopper July 27, 1937 Braswell May 16, 1939 Moody July 11, 1939 Obermaier July 11, 1939 Uhlrig Apr. 2, 1940 Kearsley Apr. 2, 1940 Failla July 21, 1942 C'reager Nov. 16, 1943 Almquist Jan. 25, 1944 Johnson Dec. 23, 1947 Clark Apr. 20, 1948 Schulze Feb. 13, 1951 FOREIGN PATENTS Country Date Great Britain Dec. 24, 1934 

